1. Using SKOS in practice, with examples from the classification domain
Antoine Isaac
Aida Slavic
UDC Seminar 2009

2. SKOS Simple Knowledge Organization System
SKOS is a model to represent KOSs on in RDF in a simple way
Not aimed at fitting everything!
Not aimed at replacing existing (non-web) formats!
Now an official W3C recommendation

3. SKOS basis SKOS offers a vocabulary for Concepts and concept schemes
Labels
Semantic relations
Notes

4. Networking controlled vocabularies in SKOS
Matching properties as conceptual relations
KOS2
animal
human
object
KOS1
animals
cats
wildcats

5. The relevance of networked KOSs
Johan Stapel, Koninklijke Bibliotheek, Den Haag

6. Pointers to SKOS deployments
SKOS implementation report
Library of Congress Subject Headings
lcsh.info
RAMEAU subject headings
stitch.cs.vu.nl/rameau
DDC
dewey.info

7. SKOS conversion example: NBC
Dutch Basic Classification
21.50 Sculpture: general
21.51 Techniques and materials

8. Representing classes as concepts
21.51 Techniques and materials

9. Relationships between classes
21.50 Sculpture: general
21.51 Techniques and materials

10. Issues with SKOS representation of classifications
Captions and labels
Languages
Time versions of classes
Coordination of classes
Auxiliary elements …

11. Issue 1: notations, captions and labels
SKOS enables representing notations
And human-readable preferred (or alternative) labels, suited for captions
21.51 Techniques and materials

12. Different choices for notations?
Can notations be SKOS preferred labels?
They make sense for users & can be displayed
We can represent them as language-neutral labels
Several choices!

13. Issue 2: Multiple languages
SKOS concepts can have labels in various languages

14. Issue 2: Multiple languages
On dewey.info: one concept per class & language
Several choices!

15. Issue 2: Multiple languages
Introducing an abstract entity that denotes the time/language-independent class
In RDF, it is possible to use other models in combination with SKOS…
Using Dublin Core's isVersionOf link

16. Raising difficult issues: what is a "concept"?
An artifact
used in descriptions, e.g., as subjects
used as a cluster for different labels with a similar meaning
in semantic relationships with other concepts
basis for Knowlegde Organization Systems
What qualifies as a concept for DDC? For UDC?
Can different choices be done?

17. Issue 3: Tracking modifications
2 RELIGION. FAITHS
21/28 CHRISTIANITY
21 Natural theology. Theodicy. De Deo 22 The Bible. Holy scripture 23 Dogmatic theology 24 Practical theology 25 Pastoral theology 26 Christian church in general 27 General history of the Christian church Christian churches, sects 29 NON CHRISTIAN RELIGIONS
NOW.....
2 RELIGION. FAITHS 21 Prehistoric and primitive religions 22 Religions of the Far East 23 Religions of the Indian subcontinent 24 Buddhism 25 Religions of antiquity 26 Judaism 27 Christianity 28 Islam 29 Modern spiritual movements

18. Creating representations of the versions
Each time-specific version should be a skos:Concept because:
They are related to other (versions of) classes
Classification act refers to a time-specific version
A book on the Bible would be wrongly classified by "22" if "22" is the notation for "Far Eastern Religions"

19. Representing versions of classes
IF WE FOCUS ON NOTATION... 22
Representing versions of classes
Using Dublin Core's isReplacedBy link

20. Notations as a reference

21. Notations as aggregations
Notations can be seen as hubs for time-specific version of classes
Using the aggregates link
from Object Reuse & Exchange (ORE) initiative

22. Tracking "Far East religions" in UDC database
CLASS ID: 16544
NOTATION: 22
DESCRIPTION:Religions originating in the Far East
*REPLACES: DESCRIPTION: Religion of Oriental peoples ID: 15999
NOTATION HISTORY [22]: YES OLD DESCRIPTION: Bible
There is interesting history information (incl. IDs) in the vocabulary management system!

23. Concepts across notations
"Far East religions" existed before: 299.5
It does not belong to 22 alone
There is a more abstract Far East Religion entity
its conceptual content may be updated while it keeps its position in the hierarchy
it might be moved in the notation hierarchy and retain its conceptual content

24. Representing concepts across notations

25. Towards stable abstract concepts?
Problem: these "abstract concept" entities are not currently explicit in UDC, there is no ID for them

26. Two different versioning & aggregation mechanisms at work

27. Conclusion SKOS is an interoperability enabler There are still issues
Different conversions reveal different choices
But that's not a new problem, really
Standardization often needs best practices & use cases
Now, it is easier to publish and compare data
As data is (will be) linked, it is even crucial to do it!
Interaction between information experts and techies is crucial

28. Thank you! Questions? Drawing inspiration from
Joseph Tennis & Stuart Sutton
Michael Panzer
Jakob Voss